The metal shell plugs are old school and had as said above a rubber insert for help in straining relief the two screw metal
strain relief. (That strips easily.) Such plugs are now I believe considered home owner grade, and or if the bushings/rubber inserts are not there to help clamp the
cord grips onto the cable are inneffective unless
friction tape is used - a better solution. Back in the day... the early 90's when knowing just enough, and working with no money in the budget... I liked the metal shell store bought
Edison plugs. I would terminate my wires in fork terminals and put them into the terminals. Insulated fork terminals would fit, one could ensure tension on the conductors from the terminals without them stripping, and didn't have to worry than about loose terminals. I probably have some still at home in this termination and
plug type.
You should not use such plugs in a theater these days. The Hubbel./
Leviton/Pass Seymore/Marinco commercial grade plugs are these days required. I love
Hubbell but only for under 14ga. in not
fitting right anything 12ga. Just not designed well for 12ga. cable. I love Pass Seymore Yellow/Black but it's a squared body, but I do love them and hardware store available. Options in
cord grip and good quality.
Leviton is company
plug standard I use. Yea, I/where I work is
OEM with them given how many plugs/connectors I buy per year... this was a choice in what brand I use by way of at times, over a thousand of them bought per year. I chose this brand and recommend it within the rules of CB due to experience and trying other brands. My go to brand of
plug.
In general, the largest problem with the use of all commercial grade plugs is the installer of them. Beyond loose terminals in forgetting to tighten one, or going lilly weak in terminating them... it's as mentioned above following the instructions on the
plug. For the metal shell and other household grade plugs, the strip length of
conductor is normally about 1/4". For commercial grade plugs the proper strip length dependant on brand is between 1/2" and 5/8" dependant on the brand.
Can't tell you how many melted terminals on commercial grade plugs I have had due to someone stripping issues of 1/4" of
insulation off a cable and putting the rest of the
insulation covered
conductor into the
terminal of a
plug... The
insulation in the way of the clamp prevents the clamp tightening suffently onto the conductors and than you have problems. I train as many people as I can on following the instructions and or terminating plugs... It's still common the problem of someone that didn't read the instructions and did the 1/4" strip length causing the problem.
Even get this from our suppliers who often
crimp the conductors (crimped
ferrule into a
plug other than
stage pin or cee form - bad idea if set screws are not directly clamping down onto conductors,) no thought of the
wire insulation making for a bad termination. Every cable from manufacturer's we get for hundreds of moving lights per year has to be inspected - marked for inspection, and normally re-terminated. Normally we color in the
UL-Listed bug at the center of the
plug with a purple if from my department, or silver sharpee dot around it if done from someone else. Not supposed to use un-marked factory
fixture cables unless inspected.
I could a lot more about the factory supplied
fixture moving light cable whips - need to inspect tension on terminals, strip length, cut off the
ferrule, not commercial grade plugs in use... but off topic.
De-list the use of your metal shell
Edison plugs in use for a replacement program to start. Upgrade to be funded in following the
current standards. On torque, 1/4 turn past
hand tight is not something than can be conveyed without inspection. Perhaps if the
plug has a torque setting to terminals, as they probably do, a torque screw
driver should be required also out of
safety at least to check/verify torque.
